Natural selection

Question 1

What is genetic diversity?

Answer 1

number of different alleles of genes in a species or population

Question 2

What is genetic diversity within a population increased by?

Answer 2

• Mutations in the DNA forming new alleles
• Gene flow

Question 3

What is gene mutation?

Answer 3

change in sequence of base pairs in DNA molecule that may result in an altered polypeptide

Question 4

Why don’t some mutations result in an altered polypeptide?

Answer 4

the genetic code is degenerate

Question 5

What is deletion?

Answer 5

When a nucleotide is randomly deleted from the sequence

Question 6

What does deletion cause?

Answer 6

changes the amino acid that would of been coded for, also changes the groups of the next three bases in the sequence

Question 7

What is substitution?

Answer 7

When a DNA base is randomly substitute with a different base

Question 8

What cause does substitution have?

Answer 8

Changes the amino acid but does not have a knock on effect on other amino acids

Question 9

What are mutagenic agents?

Answer 9

Mutagenic agents are environmental factors that increase the mutation rate of cells

Question 10

What are examples of mutagenic agents?

Answer 10

• high energy radiation
• ionising radiation
• toxic chemicals

Question 11

What is non-disjunction?

Answer 11

chromosomes fail to separate during meiosis

Question 12

What happens if abnormal gametes take part in fertilisation?

Answer 12

a chromosome mutation occurs as the diploid cell will have the incorrect number of chromosomes

Question 13

What is a chromosome mutation?

Answer 13

A change in the number of chromosomes

Question 14

What is the purpose of meiosis?

Answer 14

produces daughter cells that are genetically different to each other.

Question 15

Why are the daughter cells genetically different?

Answer 15

• independent assortment
• crossing over

Question 17

Explain crossing over?

Answer 17

The process whereby a chromatid breaks during meiosis and rejoins to the chromatid of its homologous chromosome so that its alleles are exchanged

Question 18

Explain genetic variation?

Answer 18

exists within population due to a combination of different alleles, under certain environmental conditions organisms with certain alleles will have a greater chance of survival

Question 19

What happens with organisms with alleles that have better chance of survival?

Answer 19

They reproduce and produce organisms and pass down the advantageous allele to future generations

Question 20

What are the two different types of natural selection?

Answer 20

• stabilising
• directional

Question 21

What is stabilising selection?

Answer 21

keeps allele frequency constant over time, this means things stay the same unless there is a change in environment

Question 22

What is directional selection?

Answer 22

produces a gradual change in allele frequencies over time, this usually happens when there is a change in environment and leads to an increase in beneficial alleles

Question 23

What are anatomical adaptations?

Answer 23

Structural and physical feature change

Question 24

What are physiological adaptations?

Answer 24

Biological processes within the organism

Question 25

What are behavioural adaptations?

Answer 25

The way an organism behaves